The electronics industry, being one of the high-technology industries, has been developing rapidly over the past 20 years. Along with the advancement of the modern electronic technology, various tiny and light-weight, high performance, and multi-functional electronic products are being developed. In order to develop electronic products for transmitting high-frequency electric signals and processing information efficiently, one should look for laminates with excellent dielectric properties in order to be compatible with the requirements of high-frequency electromagnetic waves gigahertz frequency (GHz) or megahertz frequency (MHz).
Laminates for high-frequency circuits are heated up and thus energy is dissipated. This leads to the decline of the completeness of high-frequency electric signals. The signal loss is influenced by various factors, mainly because of the epoxy resin forming the laminates and the properties of the glass fabrics. Glass fabrics provide the reinforcement for laminates, the dielectric constants of glass fabrics are higher than the dielectric constants of epoxy resins. Glass fabrics also have very high volume percentage. Further, glass fabrics are highly influential to the signal transmission velocity, transmission path and completeness of signals. Therefore, an in-depth investigation and research of glass fabrics are essential for selecting the suitable materials for making the laminates to cope with the fabrication technology, target properties and costs.
Generally, the reinforcements used for laminates are E glass clothes. E glass clothes have a relatively higher dielectric constant (typically 6.5). If glass clothes with low dielectric constants are used to prepare the reinforcements, e.g., quartz glass clothes (dielectric constant 3.8) and D glass clothes (dielectric constant 4.7), the dielectric constant of the laminates will be significantly lowered. However, due to the higher prices of these glass fabrics, as well as the difficulty of drilling holes, their application as the reinforcements are limited. The air permeability of normal glass fabrics is high and their yarn is wide. Not only do these properties lower the wettability of glass fabrics, they also increase the inconsistency of the substrates for carrying the signal transmission pathway.
Therefore, there is a need for metal clad laminates with lower signal loss. There is also a need for metal clad laminates with improved signal integrity and lower costs.